Poly aromatics ring opening

Poly(phenylene oxide)s undergo many substitution reactions (25). Reactions involving the aromatic rings and the methyl groups of DMPPO include bromination (26), displacement of the resultant bromine with phosphoms or amines (27), lithiation (28), and maleic anhydride grafting (29). Additional reactions at the open 3-position on the ring include nitration, alkylation (30), and amidation with isocyanates (31). 

The benefits related to the particular topology of ITQ-21 when used as heterogeneous catalyst have been reported for different processes, such as catalytic cracking [1], hydrocracking [2] or hidrogenation and ring opening of (poly)aromatics [3]... 

Over the past decade, literally dozens of new AB2-type monomers have been reported leading to an enormously diverse array of hyperbranched structures. Some general types include poly(phenylenes) obtained by Suzuki-coupling [54, 55], poly(phenylacetylenes prepared by Heck-reaction [58], polycarbosilanes, polycarbosiloxanes [59], and polysiloxysilanes by hydrosilylation [60], poly(ether ketones) by nucleophilic aromatic substitution [61] and polyesters [62] or polyethers by polycondensations [63] or by ring opening [64]. 

Colquhoum, H. M. Lewis, D. E Ben-Haida, A. Hodge, P. Ring-chain interconversion in high-performance polymer system. 2. Ring-opening polmerization-copolyetherification in the synthesis of aromatic poly(ether sulfones). Macromolecules 2003, 36, 3775-3778. 

Many authors elucidated functionalization of polymers containing reactive oxirane moieties. Epoxidized NR, BR, IR and/or the respective model hydrocarbons, poly (butadiene-co-isoprene, various epoxy resins, poly (2,3-epoxypro-pyl methacrylate) and its copolymers or grafted systems were mostly exploited. Stabilizers based on epoxidized unsaturated rubbers are of the top interest. The mechanism of the functionalization process was studied in details by means of 3,4-epoxy-4-methylheptane and 1,2-epoxy-3-ethyl-2-methylpentane as model compounds [289]. The ring opening of the asymmetric oxirane is regiospecific. Aliphatic primary amines attack the least substituted carbon atom and can be involved in crosslink formation. Aromatic primary and secondary amines are less reactive than aliphatic ones because of their lower basicity the attack on the least substituted carbon atom is however preferred too. 

Methylene-l,4,6-trioxaspiro[4,4]nonane (267) (BMTN), an orthoester synthesized from phthalide and epichlorohydrin, underwent radical ring-opening polymerization to form an aromatic poly-ketoester (268) with high thermal stability <83JPS(A)353>. 

Xie, D., Ji, Q., and Gibson, H. W., Synthesis and Ring-Opening Polymerization of Single-Sized Aromatic Macrocydes for Poly(arylene etherjs, Macromolecules, 30, 4814, 1997. 

Wholly aromatic Pis like Kapton, insoluble in common organic solvents, are usually synthesized through a two-step method PI precursors, high molecular weight poly(amic acid)s (PAAs) are readily synthesized from ring-opening polyaddition of an extra-pure dianhydride and an equimolar diamine in aprotic amide solvents such as A,A-dimethylacetamide (DMAc) and A-methyl-2-pyrrolidone (NMP), then the as-cast dried PAA films are subjected to thermal or chemical imidization. The reaction scheme and the abbreviations of polymers and monomers are shown in Fig. 1. 

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